The present invention relates to use of rosmarinic acid and/or derivatives thereof as immunosuppressive agents and/or as inhibitor of SH2 domain function. Disclosed in the present invention is that rosmarinic acid and derivatives thereof specifically inhibit the binding of ligand peptides to Lck SH2 domain, disturb the Lck-mediated signal transduction in T cells, also inhibit cytoline gene expression, and suppress immune responses in the transplanted tissue. These activities of rosmarinic acid and derivatives thereof support their applicability to treatment, prevention and/or diagnosis of graft rejection, GVHD, autoimmune diseases, inflammatory diseases, etc.

Claim:

What is claimed is:

1. A method for suppressing an immune response for treatment, prevention, or diagnosis of rejection of transplanted organ or tissue, chronic rejection, or graft-versus-hostdisease; for treatment, prevention, or diagnosis of autoimmune disease; or for treating a condition characterized by elevated levels of IL-1.beta., IL-4 or IL-6; comprising administering a rosmarinic acid, a derivative thereof or Prunella vulgarisextract.

2. The method of claim 1, wherein the rosmarinic acid is employed in the form of enantiomer or diastereomer.

3. The method of claim 1, wherein the derivative is selected from the group comprising rosmarinyl isopropyl ester, rosmarinyl ethyl ester, and (S)-rosmarinyl bis(tert-butyldimethylsilyl)ether.

11. The method of claim 9, wherein the rosmarinic acid is employed in the form of enantiomer or diastereomer.

12. The method of claim 9, wherein the derivative is selected from the group comprising rosmarinyl isopropyl ester, rosmarinyl ethyl ester, and (S)-rosmarinyl bis(tert- butyldimethylsilyl)ether.

13. The method of claim 9, wherein the method for inhibiting an SH2 domain is used for treatment, prevention, or diagnosis of rejection of transplanted organ or tissue, chronic rejection, or graft-versus-host disease.

The present invention relates to the use of rosmarinic acid and/or derivatives thereof as immunosuppressant and/or as inhibitor of the Lck (lymphocyte cell kinase) SH2 domain function.

BACKGROUND

Organ transplantation is now common for patients with end-stage renal, cardiac, hepatic or pulmonary failure. Currently, allografts of kidney, heart, lung, liver, bone marrow, pancreas (islet cells), cornea, small intestine and skin areroutinely performed. Additionally xenografts are now performed using porcine heart valves. Organ transplants, however, evoke a variety of immune responses in the host resulting in graft rejection and Graft-Versus-Host Disease (hereinafter, referred toas "GVHD").

The immune response is primarily triggered by T cells through recognition of alloantigens, and the major targets in transplant rejection are non-self allelic forms of class I and class II Major Histocompatibility Complex (MHC) antigens. In acuterejection, donor's antigen-presenting cells such as dendritic cells and monocytes migrate from the allograft to the regional lymph nodes, where they are recognized as foreign by the recipient's CD4.sup.+ T.sub.H cells, stimulating T.sub.H cellproliferation. Following T.sub.H cells proliferation, a population of effector cells (including cytotoxic CD8.sup.+ T cells and CD4+ T cells) is generated, which migrates and infiltrates to the graft and mediates graft rejection (Noelle et al., FASEB5(13):2770, 1991).

Whereas acute rejection is a T cell-dependent process, a broad array of effector mechanisms participates in graft destruction. Through the release of cytokines and cell-to-cell interactions, a diverse assembly of lymphocytes including CD4.sup.+T cells, CD8.sup.+ cytotoxic T cells, antibody-forming B cells and other proinflammatory leukocytes, is recruited into the anti-allograft response. Antigen-presenting graft cells are destroyed directly by cytotoxic CD8.sup.+ T cells. ActivatedCD4.sup.+ T cells produce interleukin-2 (hereinafter, referred to as "IL-2"), which is essential to the activation of both CD8.sup.+ T cells and B cells. Additionally, CD4.sup.+ T cells produce other cytokines such as

IFN-.gamma. and IL-4 that also contribute to the destruction of allograft. Furthermore, interferon-.gamma. (hereinafter, referred to as "IFN-.gamma.") induces increased expression of class I and class II MHC molecules on graft tissue, whichis more readily attacked by alloreactive effector cells. IFN-.gamma. enhances macrophage activity and affects many inflammatory cells leading to delayed-type-hypersensitivity reaction and inflammation causing nonspecific damage to the graft. Thesereactions appear to be the primary cause of the early acute rejection that may occur within the first few weeks after transplant. If untreated, acute rejection progresses to a rapid and severe process that causes destruction of the transplant within afew days.

In the case of bone marrow transplantation, in particular, GVHD (graft-versus-host disease) is another obstacle to survival of transplanted patient& GVHD is a disease in which transplanted marrow cells attack the recipient's cells (Storb,"Pathophysiology and prevention of graft-versus-host disease." In Advances in Immunobiology: Blood cell antigens and bone marrow transplantation, McCullogh and Sandler, editors, Alan, Inc., N.Y., p.337, 1984). A large proportion of GVHD-afflictedindividuals dies as a result of GVHD (Weiden et al., "Graft-versus-host disease in allogeneic marrow transplantation", in Biology of Bone-Marrow Transplantation, Gale and Fox, editors, Academic Press, N.Y., p37, 1980).

To protect patients from such fatal damages, various immunosuppressive agents have been employed. Currently, allograft rejection is controlled using immunosuppressive agents such as cydosporin A, azathioprine, corticosteroids includingprednisone, and methylprednisolone) cyclophosphamide. Cyclosporin A, the most powerful and most frequently used immunosuppressant, revolutionized the field of organ transplant surgery. Other immunosuppressive agents such as FK506, rapamycin,mycophenolic acid, 15-deoxyspergualin, mimoribine, misoprostol, OKT3 and anti-IL-2 receptor antibodies, have been used in the treatment and/or prevention of organ transplantation rejection (Briggs, Immunology letters, 29(1-2), 89-94, 1991; FASEB 3:3411,1989). Although the development of new immunosuppressive drugs has led to substantial improvement in the survival of patients, these drugs are associated with a high incidence of side effects such as nephrotoxicity and/or hepatotoxicity.

Because immune responses in transplantation rejection are primarily dependent on T cell, agents that suppress the functions of T cells are likely to be more efficacious drugs. Cyclosporin A (CsA) and FK506 inhibit T cell activation by inhibitingthe transcription of cytokine genes. Their action mechanism can be summarized as follows.

Cyclosporin A and FK506 bind to immunophilins such as Cyclophilins and FK506-binding proteins (FKBPs). The drug-immunophilin complexes bind to and inhibit the enzymatic activity of the Calcium- and Calmodulin-dependent serine/threoninephosphatase, Calcineurin. The inactivation of this enzyme blocks the nuclear translocation of the cytoplasmic component of the transcription factor NF-AT Nuclear factor of activating T cells) required for the expression of cytokine genes including IL-2.

However, Cyclosporin A has associated toxicities and side effects when used even at therapeutic doses. Although FK506 is about 10 to 100 times more potent than Cyclosporin A in inhibiting activation-induced IL-2 transcription in vitro and graftrejection in vivo, it also shows the side effect such as neurotoxicity and nephrotoxicity.

Rapamyycin is another potent immunosuppressant that inhibits IL-2-dependent lymphocyte proliferation. The cellular target of rapamycin-FKBP complex, mTOR has a phosphoinositide kinase activity and the mTOR signaling is related to cell cycleprogression in response to cytokines.

All these immunosuppressive drugs described above affect the T cell functions; whereas Cyclosporin A and FK506 block the step of T cell activation, rapamycin inhibits the T cell proliferation. However, the cellular targets of these agents areexpressed ubiquitously. Compounds that selectively inhibit the target molecules which is specifically expressed in immune cells, especially T cells, will undoubtedly be an ideal and more efficient immunosuppressive drug, Thus, there presently exists aneed for improved immunosuppressive agents acting specifically on immune cells.

Inhibition of T cell activation and effector functions is an attractive target for the development of drugs to treat T cell-mediated immunopathologies, like autoimmune diseases as well as transplant rejection. The antigen-specific T cellactivation is initiated by T cell receptor (hereinafter, referred to as "TCR")-mediated signal transduction in which many tyrosine kinases or phosphoproteins are involved. Progression of activated T cells into cell proliferation is subsequentlyregulated by the interaction between IL-2 and the IL-2 receptor.

A T cell-specific protein tyrosine kinase, Lymphocyte cell kinase (hereinafter, referred to as "Lck") is a key molecule of TCR-mediated signaling and plays an important role in both T cell maturation and activation. The essential role of Lck inthe various T cell function is accomplished by the interaction of SH2 and/or SH3 domain with other signaling effector molecules as well as catalytic activity of kinase domain.

SH2 domain, a conserved region in some regulatory proteins, comprises about 100 amino acids and plays a key role in the intracellular communication from a protein to another protein. Many of proteins with SH2 domain have been found to beinvolved in intracellular signal transduction. The binding specificity between SH2 domain of a protein and its ligand protein is determined by the sequences and structures of phosphotyrosine and nearby amino acids surrounding the binding site (Pawson,Nature, 373: 573-580, 1995).

The SH2 domain in Lck is one of the regulatory motifs of Lck, as is SH3 domain. When Lck is in inactive state, SH2 domain binds to intramolecular phosphotyrosine (Y505). Once Lck is activated, SH2 domain is released from autoregnlativemechanism, that is, the binding site of SH2 domain is exposed to the specific ligand proteins in T cells, allowing them to bind (Peri et al., Oncogene Res., 8: 2765-2772, 1993).

Several previous reports have tested on the key roles of Lck SH2 domain in T cell activation. One of the prominent studies exploited an Lck mutant, in which phosphotyrosine of ligand protein failed to bind to SH2 domain. In this Lck mutant, thesignal transduction systems in T cells were found to be disordered, such as the T cell activation-induced calcium signaling and the signaling for the biosynthesis and secretion of IL-2, which are essential to the T cell proliferation (Xu and Littman,Cel, 74: 633-643, 1993; Straus et al., J. Biol. Chem., 271: 9976-9981, 1996; Lewis et al., J. Immunol., 159: 2292-2300, 1997). In summary, the SH2 domain of Lck shows the indispensability for efficient .alpha. chain phosphorylation, activation-inducedintracellular Ca.sup.2+ mobilization and IL-2 gene expression in T cells.

Despite of the importance of SH2 domain in cellular signaling, little has been disclosed about the individual SH2 domain function. Study of the roles of tyrosine kinases like Lck in T cell receptor function has been hampered by lack of specificpharmacological inhibitors. Although several kinds of small molecule tyrosine kinase inhibitors such as herbinlycin and PP1/PP2 have been developed, but these drugs inhibit the kinase activity of tyrosine kinase and moreover, lack the specificity.

SUMMARY OF THE INVENTION

We have noted that Lck is specifically expressed in T lymphocyte, and that the SH2 domain of Lck plays a key role in the activation, proliferation and differentiation of T cells. With this notice, we have tried to develop a novelimmunosuppressive agent which specifically inhibit the functions of Lck SH2 domain and of T lymphocyte. In the present invention, we disclosed that rosmarinic acid and derivatives thereof efficiently suppress immune responses induced by thetransplantation of animal tissue as well as specifically inhibit the SH2 domain of Lck.

Since rosmarinic acid is a kind of domain-specific inhibitor which selectively blocks SH2 domain, it can be used to treat or prevent the diseases or their pathological effects which are mediated by interaction between SH2 domains and theirnatural ligands, and also used to treat or prevent immune disorder such as organ transplantation rejection, graft-versus-host disease, autoimmune disease and chronic inflammatory diseases.

In accordance with the present invention, there are provided novel use of rosmarinic acid and derivatives thereof as an immunosuppressant.

In addition to the use as an immunosuppressant, this invention provides use of rosmarinic acid and derivatives thereof as an inhibitor of SH2 domain.

In all aspect of this invention, the derivatives of rosmarinic acid include rosmarinyl isopropyl ester, rosmarinyl ethyl ester, and (S)-rosmarinyl bis(tert-butyldimethylsilyl)ether.

This invention also provides use of Prunella vulgaris extract as an immunosuppressant.

This invention also relates to use of Prunella vulgaris extract as an inhibitor of SH2 domain.

In such aspects of this invention, the immunosuppressant is useful for treatment, prevention, or diagnosis of rejection of transplanted organ or tissue, chronic rejection, or graft-versus-host disease.

In addition, this invention provides use of rosmarinic acid, derivatives thereof or Prunella vulgaris extract for treatment, prevention, or diagnosis of autoimmune disease.

This invention also provides use of rosmarinic acid, derivatives thereof, or Prunella vulgaris extract for treating a condition characterized by the elevated IL-1.beta., IL-4 or IL-6 level.

In addition, this invention provides use of rosmarinic acid, derivatives thereof, or Prunella vulgaris extract in combination with at least one additional immunosuppressant established.

This invention also relates to method for isolating rosmarinic acid from Prunelia vulgaris, comprising the steps of;

1) extracting active material from Prunella vulgaris by soaking it in methanol;

2) extracting active fraction with ethylacetate from the product of step 1);

FIG. 6 shows the suppressive effect of rosmarinic acid on contact sensitivity response to DNFB in mice, and

FIG. 7 shows the suppressive effect of rosmarinic acid on cytokine production of renal allografts.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides the use of rosmarinic acid as an immunosuppressant and/or as a specific inhibitor of the Lck SH2 domain. The rosmarinic acid of the present invention includes (R)-rosmarinic acid, (S)-rosmarinic acid and theracemate thereof.

The present invention also provides the use of derivatives of rosmarinic acid as an immunosuppressant and/or as a specific inhibitor of the Lck SH2 domain. The derivatives of rosmarinic acid include rosmarinyl isopropyl ester, rosmarinyl ethylester and (S)-rosmarinyl bis(tert-butyldimethylsilyl)ether.

The present invention also provides pharmaceutical composition, which contains rosmarinic acid, derivatives thereof and/or Prunella vulgaris extract. The pharmaceutical composition can be used as immunosuppressant and/or inhibitor of Lck SH2domain, particularly used for the treatment, prevention and/or diagnosis of the rejection of transplanted organ or tissue, autoimmune diseases, inflammatory diseases, etc.

In all aspects of the present invention, rosmarinic acid and derivatives thereof include (R)-rosmarinic acid, (S)-rosmarinic acid, rosmarinyl isopropyl ester, rosmarinyl ethyl ester, (S)-rosmarinyl bis(tert-butyldimethylsilyl)ether, etc. Otherderivatives may be used without departing from the scope and spirit of this invention.

In preferred embodiments, rosmarinic acid can be isolated from an extract of various herbs including Prunella vulgaris.

Rosmarinic acid is screened to be an inhibitor of the binding between Lck SH2 domain and specific ligand molecule.

In a preferred embodiment, the method for purifying rosmarinic acid from Prunella vulgaris comprises the following steps;

1) extracting active material from Prunella vulgaris by soaking it in methanol;

2) extracting active fraction with ethylacetate from the product of step 1);

In preferred embodiments, also provided are derivatives of rosmarinic acid, including rosmarinyl isopropyl ester, rosmarinyl ethyl ester and (S)-rosmarinyl bis(tert-butyldimethylsilyl)ether. The derivatives can be synthesized from rosmarinicacid or from tyrosine and caffeic acid, and those skilled in the art will appreciate that more derivatives may be readily synthesized according to the established arts and the present invention.

In a preferred embodiment, rosmarinic acid and derivatives thereof inhibit in vitro binding between SH2 domain of Lck and specific ligand peptide (see FIG. 1). More particularly, rosmarinic acid and derivatives thereof selectively inhibit theLck SH2 domain fused with glutathione-S-transferase (GST). Since rosmarinic acid and derivatives thereof interfere with the formation or stabilization of signaling complexes formed by proteins containing one or more SH2 domains and their naturalligands, they can be used to treat or prevent the diseases of their pathological effects mediated by such complexes.

In another preferred embodiment, rosmarinic acid affects the immune response-induced calcium signaling in T cells (see FIG. 2). Particularly, it was reported that the treatment of the antibodies against CD3 and CD4, the surface antigens on Tlymphocyte, stimulates T cell activation and subsequent increase of intracellular calcium level, and also known that the action of Lck is involved in these cellular events. Since rosmarinic acid suppresses intracellular calcium signaling activated byanti-CD3 and anti-CD4 antibodies, it is confirmed that it inhibits the function of Lck SH2 domain and also can be used to suppress the process of T cell activation.

In still another preferred embodiment, rosmarinic acid and derivatives thereof inhibit IL-2 gene expression in T cells. The present invention employs IL-2/luciferase reporter system as an assay for IL-2 gene expression level. Since thebiosynthesis and secretion of IL-2 leads to T cell proliferation, rosmarinic acid and derivatives thereof which inhibit IL-2 synthesis can be used to suppress T cell proliferation.

Based on such findings, rosmarinic acid and derivatives thereof can be used not only to inhibit the binding to SH2 domain of Lck and the biosynthesis of IL-2, but also to suppress the immune responses and diseases in which the functions of SH2domain and IL-2 involve.

According to preferred embodiments, rosmarinic acid and derivatives thereof suppress immune response in vitro (see FIG. 5) and in vivo (see FIG. 6). In the present invention, Mixed Lymphocyte Reaction (MLR) and contact hypersensitivity responseto DNFB are performed to verify the immunosuppressive activities of rosmarinic acid and derivatives thereof.

According to another preferred embodiment, rosmarinic acid and derivatives thereof suppress allograft rejection in animals (see table 1). In the present invention, this suppressive effect is confirmed by in vivo pharmacological test procedure,in which the survival duration of grafted skin is measured.

According to still another preferred embodiment, rosmarinic acid suppresses the transplantation-induced gene expression of various cytokines. Since it has been discovered that cytokine genes are expressed at higher level in allograft tissues,the ability of rosmarinic acid to suppress the production of cytokines was examined using the method Reverse Transcription--Polymerase Chain Reaction (RT-PCR). The result implicates that rosmarinic acid and derivatives thereof are applicable toimmunosuppression therapy for transplantation rejection and to treatment of other diseases caused by the elevation of various cytokine levels.

Based on such results, rosmarinic acid and derivatives thereof are useful in the treatment of transplantation rejection such as heart, kidney, liver, bone marrow and skin transplants; autoimmune diseases such as lupus, rheumatoid arthritis,diabetes mellitus, myasthenia gravis, multiple sclerosis and psoriasis; diseases of inflammation such as dermatitis, eczema, seborrhea and inflammatory bowel disease; and fungal infections.

In another preferred embodiment, the composition can be used for inhibiting the functions of SH2 domain of Lck or SH2-mediated cellular functions. The composition includes a therapeutically effective amounts of rosmarinic acid, derivativesthereof and/or Prunella vulgaris extract, within/without a pharmaceutically acceptable delivery vehicle. Moreover, the compositions may include other immunosuppressant drug(s), such as cyclosporin A and derivatives thereof, FK-506 and derivativesthereof, mycophenolic acid and 2-(N-morpholino)ethyl ester thereof, mycophenolate mofetil, azathioprine, corticosteroids, reflunornide, cyclophosphamide, rapamycin, OKT-3, ATG, 15-deoxyspergualin, mizoribine, misoprostol, methotrexate, anti-interleukin-2receptor antibodies and anti-lymphocyte/thymocyte antisera. The composition including additional immunosuppressant shows synergism, that is, it has an increased immunosuppressive activity relative to the sum of the effects produced by rosmarinic acid orother immunosuppressant drug used alone, allowing greater immunosuppressive activity with reduced toxicity.

In another preferred embodiment, the composition is used for treating transplantation rejection. In this regard, the composition can be used for treating rejection of an allograft or a xenograft, or complications caused by graft-versus-hostdisease. In a further embodiment, the composition used for treating transplantation rejection includes rosmarinic acid and cyclosporin A.

Rosmarinic acid and the derivatives thereof may also be administered in combination with one or more nonsteroidal anti-inflammatory agent, selected from the group including aspirin, ibuprofen, naproxen, indomethacin, didofenac, sulindac,piroxicam, etodolac, ketoprofen, meclofenamate, suprofen and tolmetin, for the treatment and/or prevention of organ transplantation rejection, graft-versus-host disease, autoimmune diseases and chronic inflammatory diseases in a mammal.

Rosmarinic acid, derivatives thereof and/or Prunella vulgaris extract may be formulated with a pharmaceutical vehicle or diluent for oral, intravenous, subcutaneous, intranasal, intrabronchial or rectal administration. The pharmaceuticalcomposition can be formulated in a classical manner using solid or liquid vehicles, diluents and additives appropriate to the desired mode of administration. Orally, the compounds can be administered in the form of tablets, capsules, granules, powdersand the like. The compounds of the present invention may also be employed with sodium lauryl sulfate or other pharmaceutically acceptable detergents to enhance oral bioavailability of such compounds.

Rosmarinic acid and derivatives thereof may be administered in a dosage ranges of about 0.01.about.1000 mg/kg, preferably 0.1.about.500 mg/kg, and may be administered 0.5.about.3 times a day.

EXAMPLES

Practical and presently preferred embodiments of the present invention are illustrative as shown in the following Examples.

However, it will be appreciated that those skilled in the art, on consideration of this disclosure, may make modifications and improvements within the spirit and scope of the present invention.

Example 1

Screening inhibitor of binding to Lck SHE domain

A novel screening system was developed in the present invention to screen a substance inhibiting the interaction between Lck SH2 domain and its ligand. In the binding assay, Lck SH2 domain expressed and purified as a fusion protein withGlutathione-S-transferase (GSI) were covalently attached to 96-well microtitre plates through amide bond formation. The immobilized proteins were subsequently allowed to bind biotinylated phosphotyrosine (Y)-containing synthetic peptide(biotin-SGSGEEPQpYEEIPI) known as a high affinity ligand for the Lck SH2 domain.

For attachment to 96-well microtitre plate, 1 .mu.M of purified fusion protein (GST-Lck SH2) was reacted for 2 hours at room temperature. Added to the binding assay were 1 .mu.M of the biotinylated synthetic peptide (the ligand of Lck SH2domain) and a candidate for the inhibitor. The candidates were thousands of natural products including various kinds of Streptoryces, fungi and herbs extract. Binding reaction was performed for 2 hours at room temperature, allowing the competitiveinhibition of the binding between GST-Lck SH2 and the peptide ligand. Then peroxidase-conjugated streptavidin (Pierce, USA) was added into the mixture so that added conjugates can be bound to biotinylated peptide. After unbound conjugates were washed,coloring reaction was performed to measure the activity of immobilized peroxidase, or the binding activity of the peptide to SH2 domain in the presence of the candidate added. More particularly, the coloring reaction was initiated by adding3,3,5,5-tetramethyl benzidine (substrate) to the reaction mixture. After 30 minutes, the reaction was stopped by adding 0.8M sulfuric acid, and immediately brought to the spectrophotometry of measuring absorbance at 450 nm.

This screening procedure resulted in the discovery of an inhibitory substance, which was isolated from a perennial herb Prunella vulgaris.

Example 2

Isolation and purification of rosmarinic acid from Prunella vulgaris extract

Dried Prunella vulgaris (600 g) purchased from local herbalist was soaked in methanol (10.about.20L) at room temperature. After 3-5 days, methanol extract was concentrated in vacuum, resuspended in distilled water, and extracted in ethylacetate. The ethylacetate extract was fractionated based on inhibitory activity of binding to SH2 domain of Lck.

The fraction with highest activity was concentrated in vacuum and dissolved in small dose of chloroform:methanol (20:1), and then loaded into silica gel column chromatography After the fraction without the inhibitory activity was washed withchloroform: methanol (20:1), active fraction was eluted with chloroform: methanol: water (20:10:1.about.10:5:1).

The active fraction was concentrated in vacuum, dissolved in small volume of methanol, and then loaded into Sephadex LH-20 (Sigma), using methanol as developing solvent.

The eluted fraction was loaded to high-performance liquid chromatography (HPLC), in which 45% methanol and 5% phosphoric acid solution was used as developing solvent through YMC-Pack C18 column (2 cm inner diameter.times.15 cm outer diameter),with 4 ml/min of flow rate and 254 nm of UV wavelength. The active fraction with 22 minutes of elution time had peaked in the level of inhibitory activity of binding to SH2 domain. This fraction was absorbed in diaion EP-20 and eluted with 100%methanol, so that inhibitory substance (50 mg) for binding to SH2 domain of Lck can be obtained.

The physical and chemical properties of the purified product were shown as follows;

The compound (1) (1 g, 3.5 mmol) was dissolved in water (20 ml) and cooled in ice-water bath. This solution was dropwisely added into NaNO.sub.2 (0.4g, 5.8 mmol) dissolved in water 12 ml and slowly stirred. After the solution was stirred atroom temperature for 20 hours, ammonium sulfate

(204 mg, 1.54 mmol) was added and stirred for further 1 hour. The crude product was extracted in ethylacetate, and the separated organic phase was dried on MgSO.sub.4. Excess solvent was removed by rotary evaporator. Flash chromatography(elution system, n-Hexane: ethyl acetate, 85:15 to 6:4) gave yellow oil as a major product (0.7 mg, 81%).

To caffeic acid (4 g, 22.2 mmol) dissolved in CH.sub.2 Cl.sub.2, tert-butyldimethylsilyltriflate and triethylamin were added, and the solution was stirred for 17 hours. The reaction solution was washed with 10% HCl solution (2.times.20 ml) andwater (2.times.20 ml). The organic phase was dried on MgSO.sub.4 and concentrated. The colorless solid was purified by flash chromatography and dissolved in 50% methanol (200 ml). After potassium carbonate (1.8 g, 11 mmol) was added, the reactionsolution was stirred at room temperature for 6 hours. The solid was removed by filtration, and then the filtrate was acidified with a small dose of hydrochloric acid. After the acidified product was extracted with ethylacetate and washed with water(3.times.20 ml), the combined organic phase was dried on MgSO.sub.4 and concentrated. The colorless solid was obtained by flash chromatography. ##STR8##

The purified solid obtained in the Example 5(4.23 g, 5.97 mmol) was dissolved in THF in N.sub.2 atmosphere and tetra-n-butylammonium fluoride (1.0M in THF, 12 mL, 12 mmol) was added. After stirred for 15 minutes, the solution was washed withwater and extracted with ethylacetate. The separated organic phase was dried on MgSO.sub.4 and concentrated. Flash chromatography gave yellow oil as a major product (1.47 g, 51%).

The following Examples illustrate the efficacy of rosmarinic acid and derivatives thereof as an inhibitor of Lck SH2 domain or as an immunosuppressant.

However, it will be appreciated that those skilled in the art, on consideration of this disclosure, may make modifications and improvements within the spirit and scope of the present invention.

Example 7

Inhibition of in vitro binin between Lck SH2 domain and specific phosphotyrosyl peptide

The activities of rosmarinic acid and derivatives thereof to bind SH2 domain of Lck were investigated in this invention by using the in vitro binding assay system of Example 1.

Various concentrations (0.03.about.300 .mu.g/ml) of rosmarinic acid solution, which was isolated from Prunella vulgaris or derivatives thereof, were added to the protein-coated micro-well mixed with phosphopeptide solution. The binding ofbiotiyated pY peptides was detected by the streptavidin-conjugated horseradish peroxidase (HRP).

In addition to treatment of rosmarinic acid, treatment of derivatives of rosmarinic acid such as rosmarinyl isopropyl ester, rosmarinyl ethyl ester and (S)-rosmarinyl bis(tert-butyldimethylsilyl)ether and (S)-rosmarinic acid resulted in acompetitive inhibition of binding to SH2 domain. In these cases, IC.sub.50 were 1, 4, 13 and 10 .mu.g/ml, respectively.

Rosmarinic acid and derivatives thereof are, therefore, useful as reagents for biological research since, for example, they can uncouple or block a particular signal transduction pathway of interest. Rosmarinic acid and derivatives thereof,which interfere with the formation or stabilization of signaling complexes formed by proteins containing one or more SH2 domains and their natural ligands, could be used to treat or prevent the pathological diseases mediated by such complexes.

Example 8

Inhibitory effect on the Signal transduction of T cell proliferation

Since rosmarinic acid isolated from Prunella vulgaris and derivatives thereof inhibit binding of ligands to SH2 domain of Lck, it is supposed that these inhibitory effects will disturb the signal transduction system of T cell proliferation,changing the pattern of intracellular calcium mobilization.

The antigen-specific T cell activation is initiated by TCR-mediated signal transduction in which many tyrosine kinases or phosphoproteins are involved. The progression of activated T cells into cell proliferation is subsequently regulated by theinteraction between IL-2 and the IL-2 receptor. Particularly, it was reported that the treatment of the antibodies against CD3 and CD4, the surface antigens on T lymphocyte, stimulates T cell activation and subsequent increase of intracellular calciumlevel, and also known that the action of Lck is involved in these cellular events. Therefore, it was investigated in the present invention whether rosmarinic acid could inhibit the increase of intracellular calcium level, which was induced by Tlymphocyte activation.

Fura-2/AM (Calbiochem, San Diego, Calif., USA), a fluorescent indicator of intracellular calcium, was loaded into Jurkat cells, and various amounts (0.5 .mu.g, 1 .mu.g, 10 .mu.g, 50 .mu.g) of rosmarinic acid, isolated from Prunella vulgaris, wastreated to the cells for 10 minutes. The cells were treated with anti-CD3 and anti-CD4 antibodies, and then the fluctuation of intracellular calcium level was recorded by the amount of fluorescence emitted from the cells.

FIG. 2 shows the dose-dependent inhibitory effect of rosmarinic acid on the calcium level. Thus, it was disclosed that rosmarinic acid, isolated from Prunella vulgaris in the present invention, has an inhibitory activity to intracellular calciummobilization.

Example 9

Inhibition of TCR stimulation-induced IL-2 gene expression

Since rosmarinic acid and derivatives thereof selectively inhibit Lck function, we tested whether these compounds could suppress the IL-2 activation-induced IL-2 production, which is responsible for the progression into T cell proliferation. Theeffects of rosmarinic acid and derivatives thereof on the level of IL-2 gene expression were tested by using the IL-2-luciferase reporter system, in which cultured cells were transfected with a reporter plasmid. The plasmid was constructed by fusion ofthe IL-2 promoter sequence with the structural gene of luciferase.

10.sup.6 Jurkat T cells were transfected with IL-2-luciferase reporter plasmid by use of Superfect.TM. (Qiagen Inc.). After incubation for 24 h, cells were treated with various drugs (8 .mu.M rosmarinic acid or derivatives thereof, 8 .mu.MCyclosporin A, 8 .mu.M FK506, 8 .mu.M LY294002) for 30 min prior to T cell activation. Cells were activated by incubation for 14 h on a 35 mm dish coated with 5 .mu.g/ml anti-CD3 antibody (UCHT1, Pharmingen) and/or anti-CD4 antibody (RPA-T4, Pharmingen)and then harvested. For PMA plus Iononycin stimulation, 5 ng/ml of PMA and 500 ng/ml of lonomycin were added to the culture media and incubated for 14 h. Luciferase activity was determined three times in duplicate for each experiment with a Bertholdluminometer LB953.

Rosmarinic acid inhibited the TCR-induced IL-2 gene expression more efficiently than other immunosuppressants did (see FIG. 3). Furthermore, the luciferase activities in the experiments using derivatives of rosmarinic acid such as rosmarinylisopropyl ester, rosmarinyl ethyl ester and (S)-rosmarinyl bis(tert-butyldimethylsilyl)ether and (S)-rosmarinic acid were inhibited as much as rosmarinic acid (see FIG. 4).

Since rosmarinic acid and derivatives thereof effectively suppress T cell activation, they can be used to treat and/or prevent the diseases involved in T cell-mediated immune responses, such as autoimmune diseases, chronic inflammatory diseasesas well as transplantation rejection and GVHD.

Example 10

Inhibition of T cell proliferation

As Lck is a T cell-specific tyrosine kinase exerting its activity for T cell activation and proliferation, in present invention, the inhibitory activity of rosmarinic acid to T cell proliferation was tested. The mixed lymphocyte reaction (MLR)test described below may be used to demonstrate that the compounds of this invention have the ability to suppress or inhibit an immune cell reaction. The MLR is used for the determination of transplantation compatibility between the donor (graft) andthe recipient (Park and Good, p71, in Tissue typing and organ Transplantation, 1973, Academic Press Inc., N.Y.). The MLR, in which immune response is elicited by mixing two kinds of lymphocytes isolated from different species or individuals, representsthe activity of the immune response by growth rates of cells.

Splenocytes (1.times.10.sup.5 /well) isolated from Balb/c and C57BL/6 mice were mixed and incubated at 37.degree. C. in a humidified incubator. At 5th day, [methyl-.sup.3 H]-thymidine (0.5 .mu.Ci/well) was added to the cultures, and then theincorporated amounts into the cultures were measured next day. During all procedure, Cyclosporin A, rosmarinic acid, derivatives thereof or (S)-rosmarinic acid was treated at an indicated concentration.

The MLR is an in vitro immune response. Inhibition of the MLR immune response is a standard assay used in the field of immunology, which is considered to be indicative of in vivo immunosuppressive activity. In particular, activity in the MLRindicates that rosmarinic acid and derivatives thereof should be effective in preventing organ transplantation rejection and GVHD. Thus, in view of the results presented in the application, rosmarinic acid and derivatives thereof are expected to beefficacious in treating these diseases.

Example 11

Inhibition of immune response in vivo

In vivo test procedure evaluating the immunosuppressive activity was performed using contact hypersensitivity response to DNEB (2,4-dinitroflourobenzene). Contact sensitivity to DNFB has been extensively studied and characterized in the mouse todetermine the regulatory mechanisms involved in cell-mediated immune responses (Claman et al., Immunol. Rev. 50:105, 1980; Young and Young, "Cutaneous Models of Inflammation for the evaluation of topical and systemic pharmacological agents" inPharmacological a methods in the control of inflammation (Chang and Lewis, Eds.), Alan R. Liss, Inc., N.Y., York, pp215-231, 1989). This is an antigen-specific T cell-mediated inflammatory response that represents delayed-type hypersensitivity (DTH)reactions seen in both humans and other mammals. The contact sensitivity animal model is used routinely in many laboratories for pharmacological screening of anti-inflammatory agents and agents for the treatment of autoimmune diseases.

Sensitization and elicitation of contact sensitivity reaction were performed as described by Schenius et al.(Scheynius, 1804, JI). The procedure is summarized as following. Balb/c female mice were used at 8 weeks of age. Twenty .mu.l of 0.5%DNFB (Sigma Chemical Co.) in 4:1 diluted acetone: olive oil (Sigma Chemical Co.) was painted on each shaved abdominal skin for 2 successive days. Four days later, the mice were challenged by applying 10 .mu.l of 0.2% DNFB in the same vehicle to eachside of each ear. Cydosporin A and rosmarinic acid were treated through intramuscular administration at the indicated doses from 0 to 5 day. Ear thickness was measured using engineer's micrometer (Mitutoyo Co. Mfg. Ltd., Tokyo) 24 h afterpostchallenge.

The treatment with rosmarinic acid (5-50 mg/kg/day) or cyclosporin A on 6 consecutive days during the induction phase dose-dependently suppressed the DNFB-induced contact hypersensitivity (FIG. 6). Rosmarinyl isopropyl ester, rosmarinyl ethylester, (S)-rosmarinyl bis(tert-butyldimethylsilyether and (S)-rosmarinic acid also showed dose-dependent suppression. The present results show that rosmarinic acid and derivatives thereof can suppress the helper T cell function and memory

T cell formation in vivo.

Based on the results of these standard pharmacological test procedures, the compounds are useful in the treatment of transplantation rejection such as heart, kidney, liver, bone marrow and skin transplants; autoimmune diseases such as lupus,rheumatoid arthritis, diabetes mellitus, myasthenia gravis, multiple sclerosis and psoriasis; diseases of inflammation such as dermatitis, eczema, seborrhea and inflammatory bowel disease; and fungal infections.

Example 12

Inhibition of graft rejection

The abilities of rosmarinic acid and derivatives thereof to induce immunosuppression were established in vivo standard pharmacological test procedures. In vivo procedure evaluated the survival time of a skin graft.

Experimental allograft rejection was performed by grafting allogeneic C57BL/6 (H-2b) mouse tail-skin onto Balb/c (H-2d) recipient mice. Rosmarinic acid and derivative thereof were administered intramuscularly from the day of the transplantationuntil rejection. Cyclosporin A was used as test control, whereas untreated recipients serve as rejection control. Full-thickness donor (C57BL/6) tail skin grafts (square pieces 2.0.times.2.0 cm) were transplanted onto the lateral thorax of recipientmice (Balb/C) and covered with sterile bactericidal gauze. The entire chest was then wrapped with an elastic bandage. Either rosmarinic acid, derivatives thereof (15 mg/kg/day) or Cydosproin A (50 mg/kg/day) of liposomal preparation was intramuscularlyadministered daily to the transplanted animal at the mentioned doses until rejection. Skin graft were monitored daily after the removal of the bandage on day 6. Rejection was defined as more than 90% necrosis of the graft epithelium.

As shown in table 1, rejection of allografts in the empty vehicle-treated control group started on day 7. About 50% of the allografts in the control group were rejected on day 9. Rosmarinic acid and derivatives thereof at doses of 15 mg/kg/dayshowed significant prolonged effect of skin graft survival. The mean survival time (MSI) of skin grafts was 9.6 days in the control group and was 14.0 days for the group of mice treated with rosmarinic acid at 15 mg/kg/day (P <0.01). Cydosporin Awas also effective at doses of 50 mg/kg (MST=13.4 days) similar with previous reports, in this system.

In addition, rosmarinic acid or derivatives thereof utilized in the present invention synergize with Cycolsporin A in inhibiting skin graft rejection in vivo. Their dose-lowering synergism with Cyclosporin A means that in therapeuticimmunosuppression they can be expected to avoid side effects.

According to one important aspect of the invention, it has been discovered that rosmarinic acid has the ability to suppress cytokine genes expressed at higher level in allograft tissues. The implications of this finding, for use inimmunosuppression therapy and for use in treatment to other diseases caused by the elevation of these cytokines are discussed in this Example.

The ability of rosmarinic acid to suppress the production of cytokines was examined using the method RT-PCR. Balb/c recipients transplanted from C57BL/6 donor were killed at 7 day after the subcapsular kidney transplantation. Renal allograftswere harvested and total cellular RNA was extracted and analyzed for the expression of various cytokine mRNA. Using a serniquantitative PCR method, we temporally analyzed mRNA levels of IL-1.beta., IL-2, IL-4, IL-6 and IFN-.gamma..

We determined the effect of rosmarinic acid (daily dose; 25 mg/kg/day) as well as Cyclosporin A (daily dose; 50 mg/kg/day) administered by intramuscular injection for 7 days. RT-PCR assays used to detect cytoline messages showed that rosmarinicacid markedly inhibited IL-2, IL-4, IFN-.gamma., IL-6 and IL-1.beta. MRNA transcription in allograft transplants, whereas Cyclosporin A inhibited the expression of IL-2, IFN-.gamma. and IL-1.beta.. The cytokine levels of PCR products were normalizedby .beta.-actin mRNA used as a control. IL-4 and IL-6 were significantly reduced by rosmarinic acid but not by Cydosporin A implying that rosmarinic acid suppressed both Th1 and Th2 cytokine expression whereas cyclosporin A can mainly inhibit Th1cytokines. For IL-2 and IL-1.beta. suppression, rosmarinic acid exerted more potent activity than that of Cyclosporin A. These observations strongly suggested that rosmarinic acid can be a prospective immunosuppressant which affects various immuneresponses related to graft rejection or T cell-mediated immunopathologies, more extensively.

The kidney grafts removed from the transplanted recipients treated with rosmarinic acid (25 mg/kg/day) for 7 days were immediately frozen in liquid nitrogen. Total RNA from the grafts was isolated using TRIZOL.RTM. LS Reagent (LifeTechnologies), incubated at room temperature for 15 min after addition of chloroform, extracted with phenol/chloroform, and precipitated with isopropanol. Isolated total RNA was then quantitated spectrophotometrically. Total RNA from the graft (1.mu.g) was performed using Titan.TM. One Tube RT-PCR System (BM) according to the manufacture's protocol. The PCR was done in a 50 .mu.l volume containing 1.times. RT-PCR buffer with Mg.sup.2+, 0.2 mM each dNTP(dATP, dGTP, dCTP and dTTP), 10U RNaseinhibitor, enzyme mix (AMV and Expand.TM. High Fidelity PCR-System), 5 mM DTT solution and 0.4 .mu.M appropriate primer pair. Primer sequences for IL-2, IFN-.gamma., IL-4, IL-6, IL-1.beta. and .beta.-actin were obtained from previous reports. The PCRproducts of IL-2, IFN-.gamma., IL-4, IL-6, IL-1.beta. and .beta.-actin are 226, 336, 222, 229, 320 and 568. The number of amplification cycles was 25. An aliquot (15 .mu.l) of the PCR product was electrophoresed on 2% agarose gel, and amplified DNAfragments were stained with ethidium bromide.

3) Primers

The PCR primers are described by SEQ ID NO: 1 to 12. Primers was named for the corresponding gene: m indicates mouse; this is followed by the gene name; F represents forward orientation and R does reverse. For example, IL-2F represents theforward primer used in the PCR of IL-2. Annealing temperatures for all the primers were 52.degree. C., except for 56.degree. C. for .beta.-actin.

Example 14

Parenteral administration test for acute toxicity using rat

We carried out following experiment to find out the acute toxicity of rosmarinic acid and derivatives thereof.

Acute toxicity was examined using 6week-old SPF SD type rat. As liposomal form, I g/kg of rosmarinic acid, rosmarinyl isopropyl ester, rosmarinyl ethyl ester, (S)-rosmarinyl bis(tert-butyldimethylsilyl)ether or (S)-rosmarinic acid wasintramuscularly injected into two mice per experimental group. After injection, mice were observed in terms of clinic symptom and change in weights of mice, and brought to blood test and autopsy so as to investigate the abnormalities of abdominal andthoracic organs. As a result, all tested animals were survived, and there was no striking clinic symptom, change in weights or other toxic effect. All the examined compounds did not elicit any toxic effect when injected to rats within the range of 1g/kg, thus proved to be safe compounds for parenteral administration.

Industrial Applicability

As disclosed by the preferred embodiments, rosmarinic acid and derivatives thereof inhibit the binding to and the function of Lck SH2 domain. This inhibitory effect of rosmarinic acid and derivatives thereof leads to the modification of calciumsignal transduction system in T cells; the suppression of IL-2 gene expression in T cells; the suppression of immune responses both in vitro and in vivo; the suppression of graft rejection; and the suppression of cytokine gene expression in graftedtissues. Thus, rosmarinic acid and derivatives thereof are useful for the inhibition of binding to Lck SH2 domain, the suppression of cytokine-mediated immune responses, and the suppression of graft rejection, autoimmune diseases and inflammatorydiseases. Since rosmarinic acid and derivatives thereof selectively inhibit the SH2 domain of Lck, a T cell-specific protein, they evoke less side effects on patients than the established immunosuppressants.

Those skilled in the art will appreciate that the conceptions and specific embodiments disclosed in the foregoing description may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes ofthe present invention. Those skilled in the art will also appreciate that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims.